Alpha-Beta move generator can look 2 plays (4 plies) ahead on a 4x4 board and blocks every possible attempt by the player to connect 3.

It should be possible to play on larger boards when the computers 'move' is changed from playing a tile to picking the player's next available color.

src/model/Referee.java

@@ -1,7 +1,13 @@
 package model;
 
+import org.apache.log4j.Logger;
+
+import player.AlphaBetaComPlayer;
+import player.HumanPlayer;
+import player.Player;
 import view.BoardPanel;
 import view.MessagePanel;
+import view.ScorePanel;
 import model.Board.TileColor;
 
 public class Referee implements Runnable {
@@ -10,26 +16,28 @@ public class Referee implements Runnable {
 	public static final String GAME_OVER = "Game over!";
 	public static final String PLAYER_TURN = "Waiting for the player's move.";
 
+	public static final Logger LOGGER = Logger.getLogger(Referee.class
+			.getName());
+
 	private final Board board;
 	private final HumanPlayer humanPlayer = new HumanPlayer();
-	private final Player cc;
+	private final Player computerPlayer;
 
-	private boolean playerTurn;
 	private BoardPanel boardPanel;
-	private int score = 0;
 	private MessagePanel messagePanel;
+	private ScorePanel scorePanel;
 
 	public Referee() {
 		board = new Board();
-		cc = new RandomComPlayer();
-		playerTurn = true;
+		computerPlayer = new AlphaBetaComPlayer();
 	}
 
 	@Override
 	public void run() {
 		int plies = 0;
 		while (!isOver()) {
-			if (playerTurn) {
+			scorePanel.updateScore(getPlayerScore());
+			if (board.isPlayerTurn()) {
 				boolean wasInterrupted = false;
 				while (!humanPlayer.isReady()) {
 					try {
@@ -39,7 +47,8 @@ public class Referee implements Runnable {
 					}
 				}
 				if (wasInterrupted) {
-					System.out.println("Interrupted while waiting for human to move!");
+					System.out
+							.println("Interrupted while waiting for human to move!");
 				} else {
 					Move mv = humanPlayer.getMove(board);
 					if (board.getTile(mv.getCell().r, mv.getCell().c) == TileColor.NONE) {
@@ -49,79 +58,65 @@ public class Referee implements Runnable {
 					}
 				}
 			} else {
-				Move mv = cc.getMove(board);
+				Move mv = computerPlayer.getMove(board);
 				playToken(mv);
 			}
-			
+
 			messagePanel.updateMessage(getMessage());
 			boardPanel.updateIcons();
-			System.out.println("plies: " + plies++);
+			LOGGER.info("plies: " + plies++);
 			try {
 				Thread.sleep(1000L);
 			} catch (InterruptedException ie) {
-				System.out.println("Interrupted while waiting for human view ply!");
+				System.out
+						.println("Interrupted while waiting for human view ply!");
 			}
 		}
 	}
 
 	public Player getComputerPlayer() {
-		return cc;
+		return computerPlayer;
 	}
 
 	public HumanPlayer getHumanPlayer() {
 		return humanPlayer;
 	}
-	
+
 	public String getMessage() {
 		if (isOver()) {
 			return GAME_OVER;
-		} else if (isPlayersTurn()) {
+		} else if (board.isPlayerTurn()) {
 			return PLAYER_TURN;
 		} else {
 			return COM_TURN;
 		}
 	}
-	
-	public boolean isOver() {
-		for (int r = 0; r < Board.NUM_ROWS; r++) {
-			for (int c = 0; c < Board.NUM_COLS; c++) {
-				if (board.getTile(r, c) == TileColor.NONE) {
-					return false;
-				}
-			}
-		}
 
-		return true;
+	public int getPlayerScore() {
+		return board.getTurn();
 	}
-	
-	private boolean isPlayersTurn() {
-		return playerTurn;
-	}
-	
-	public int getScore() {
-		return score;
-	}
-	
+
 	public TileColor getTile(int r, int c) {
 		return board.getTile(r, c);
 	}
 
+	public boolean isOver() {
+		return board.isTerminalState();
+	}
+
 	public void playToken(Move move) {
-
-		board.setTile(move.getCell(), move.getColor());
-
-		if (playerTurn) {
-			score++;
-		}
-
-		playerTurn = !playerTurn;
+		board.playTile(move.getCell(), move.getColor());
 	}
 
 	public void setBoardPanel(BoardPanel boardPanel) {
 		this.boardPanel = boardPanel;
 	}
-	
+
 	public void setMessagePanel(MessagePanel messagePanel) {
 		this.messagePanel = messagePanel;
 	}
-}
+
+	public void setScorePanel(ScorePanel scorePanel) {
+		this.scorePanel = scorePanel;
+	}
+}